Magneto-electric automatic interrupter



1927. Sept M. GREINER MAGNETO ELEEJTRIC AUTOMATIC INTERRUPTER .Fil'edMayl'Y. 192s I/Vztnsses: 4 I Inventor:

Patented Sept. 20, 1927.

UNITED STATES.

MAX GREINER, OI CHABLOTTENBURG, GERMANY.

MAGNE'IO-ELECTRIC AUTOMATIC INTERRUPTER.

Application filed May 17, 1928, Serial No. 109,658, and in Germany May26, 1925.

Magneto-electric automatic interrupters 7 serving for the delivery'ofmechanical oscillations and constructed partly like a' magnetic hammerbreak and partly like a sliding contact, require for a high eificiency,in respect of the oscillations delivered, that the current beinterrupted at the end of the working stroke of the armature only, whileit can be switched-on either at the beginning of the working stroke oralready during the return stroke of the armature, as the influence onthe efficiency is rather small. As the contact break is positivelyoperated by the oscillating armature, at the first switching-on theattraction force of the electromagnet up to the attainment of thecut-out position at each deflection of the armature from its zeroposition must be greater than the counteracting s ring power of thearmature elasticity. T is requires a comparatively high magneto-electricexcitation that highly exceeds the want for the armature oscillatingwith full amplitude. This results in an undue current consumption and ina noxious action upon the contacts which, as known, become the lessreliable the stronger is the current flowing therethrough.

Said drawbacks are overcome by the pres-- ent invention in that theoperative oscillating member (armature) is coupled with the controlcontact by a freely oscillating member of lower natural frequency thanthe operative member. Said coufpling member may, in--its sim lest form 0construction, consist of a bla e sprin carrying the control contact andload by an additional mass. oscillation forms according to the ratiobetween the drivingfrequency and its natural frequency. If the former islower than the latter, the whole spring withv the additional massoscillatespractically in phase coincidence with the drive. If'thefrequency of the drive is increased beyond the resonance, the amplitudeof the additional mass is quickly decreased to a fraction of theamphtude'of the drive; the additional mass oscillating then in phasedifference to the drive.

Intermediary points of the spring oscillate thus partly in phasecoincidence with, and partly in phase difference to, the drive.

. Said oscillation forms known er so are utilized for the arrangementaccor 'ng to the present invention in such a way that at the firstattraction of the armature, which due Such a spring oscillates indifierent.

to the inertia of its mass and directed against the spring power of thearmature takes place in a comparatively slow way, a point of thesprlngoscillating in phase coincidence opens the contact already after atrifling deflection of the armature. The following oscillations of thearmature occur, however, with its natural frequency, that is higher thanthat of the coupling member. As the additional mass then oscillates inphase difference to the armature, the armature operating the cou lingmember must first attain a lar er de ection in order that the contactpoint oscillating with smaller amplitude opens the contact. Except forthe first time, the current interruption thus takes place almostmdelpendently from the attained amplitude of t e armature always nearthe end of the stroke. The thereby required early reswitching-on of thecurrent at the beginning of the return stroke is practically without noxous influence.

In order not to disturb the coupling spring in its oscillation forms bythe counter-contact, the latter is, according to the invention, alsoelastic, for instance arranged on a s ring, so that at the returnoscillation of t e coupllng spring it can yield beyond the zeroposition; Furthermore, the oscillation energy of the coupling member,with referenceto that of the operative armature, must be small only, inorder to influence the natural frequency of the armature as little aspossible by the coupling member.

Heretofore, the arrangement of an automatic interrupter for buzzerpurposes has been known, in which the armature carries a contactpendulum that at its free end is loaded b an additional mass. Saidpendulum stri es, however, against a fixed abutment forming acounter-contact. It comes thus again at rest after each stroke and mustbe accelerated afresh by the armature. Therefore, it cannot assume thedifferent 0scillation forms essential for the operation.

of the arrangement according to the presentinvention.

If, in the improve arrangement, for the operation of the contact a pointof the coupling spring is chosen that, as afore stated, oscillates firstin phase coincidence with and then in phase diiference to the armature,and thecounter-contact sprin" is loaded by such alarge additional massthat its natural frequency is lower than that of the armature,

iio

grammatically two appropriate constructional forms of the subject matterof the present invention:

Fig. 1 shows an automatic interrupter constructed like a magnetic hammerbreak;

Fig. 2 shows part of an interrupterwith a sliding contact;

Figs. 3 and 4 indicate, on a larger scale, the actionof the couplingmember with a magnetic hammer break and with a sliding contactrespectively, the dot-and-dash lines in the two latter figuresindicating the normal position of rest of the parts.

Referring to Fig. 1: The electromagnet a has its oscillating armature 0suspended from ablade spring 6, while on said armature a second bladespring d is fixed and fitted with a control contact e and at its freeend with an additional mass 7. The counter-contact g for said controlcontact 0 is mounted on a blade spring h which can be adjusted by meansof a set-screw i in such a way that in the position of rest of thearmature c and of the spring (1 the two contacts 6 and g touch oneanother with slight contact pressure. The mass 7 is so determined thatthe natural frequency of the spring at is considerably lower than thatof the armature 0. The connection of the arrangement is thatconventional with interrupters of similar kind.

The interrupter illustrated in Fig. 2 is distinguished from that aforedescribed by having the counter-contact g loaded by an additional mass mthereby forming a sliding contact.

If, in the interrupter shown in Fig. 1, the circuit is closed by aswitch a, the electromagnet a slowly attracts the armature 0 against theaction of spring I). At this first slow attraction of the armature a,the coupling spring ai with its control contact e follows the movementof the armature in phase coincidence, in that the contact 6 participatesin the full amplitude of the movement of the armature, so that after atrifling deflection of the armature from its zero position the firstinterruption between the contacts 6 and 9 takes place. This is indicatedin Fig. 3 by dotted lines. Thereupon, the armature returns at a speedthat corresponds to its natural frequency. Consequently, the mass f thenoscillates in phase difierence to the armature, as indicated in Fig. 3by full lines. Thus, in spite of increasing amplitude of the armature,the opening of the contacts 6, g

takes place at a large deflection of the armature only, about near theend of its stroke.

In the arrangement shown in Fig. 2, the additional mass 7 of thecoupling spring J is also so determined that it oscillates initlally inphase coincidence with and then in phase difference to the armature c.The

contact a of the spring d is located nearer to the additional mass 7.The additional mass mon the counter-contact g is so determine-d that thenatural frequenc of the spring h is lower than that of t e armature c.The position of rest of the spring 72. is so adjusted by means of theset-screw i that the two contacts 6 and g touch one another with weakpressure. At a closing of the circuit, thecontacts e, g are interruptedafter a. trifling movement of the armature 0, as at the slow speed ofthe first attraction of the armature the springs d and h participate inthe movement of the armature in phase coincidence therewith until thezero position of the spring h is exceeded. At the further oscillationsof the armature, the additional mass 7 and the contact 6 oscilla'te inphase difference to the armature, as shown in Fig. 4. The contact causesthe contact 9 with the additional mass m to participate in its movementuntil the end of the stroke. The then occurring retardation of thecontact e is, however, not followed by the counter-contact g, but thelatter oscillates further due to its inertia increased by the additionalmass m and thereby eftects t e interruption.

To avoid undesirable resonances at the change of the spring 03 from oneoscillation form to another one, it is recommendable to provide thespring d with a weak damping consisting, for instance, of a weak bladespring a: (Fig. 2) fixed at one end and bearing with slight frictionressure against the free end of the spring or of an oil brake, or of anyother suitable contrivance. 'Said damping results further in a phaselagging, favourable for an extension of the current closing time, of thespring 03 behind the drivin armature.

The improved arrangement is particularly adapted for use in connectionwith apparatus working with automatic interruption and serving for thedelivery of mechanical oscillations of high periodicity, for instancefor driving the main contact of spark coils, for shaking apparatus,automatic oscillation producers,and the like.

What I claim, is:

1. In a magneto-electric automatic interrupter for the delivery ofmechanical oscillatlons. the combination with an operative oscillatingpart, of an oscillatory coupling member fixed to said part and having alower natural frequency than the latter, a control contact on saidcoupling member, a resiliently mounted counter-contact for said controlcontact, and an additional mass on said counter-contact.

2. In a magneto-electric automatic interlations, the combination with aspring-susresiliently mounted counter-contact, an adpended armature ofan electromagne't, of an ditional mass on said counter-contact, and a Voscillatory coupling spring fixed to said ar-' weak damp' g for saidcoupling spring for 10 mature and having a lower natural fresaid controlcontact.

6 quency than the latter, an additional mass In testimony whereof I havehereunto set on the free end of said coupling spring, a my hand. controlcontact on said coupling spring, 8 MAX GREINER.

